Retrievable packers typically have a sealing system and anchoring slips that are set in a variety of ways including axial compression with a setting tool. There is generally a lock to hold the set position to allow the setting tool to be released. Release of the packer involves defeat of the locking system that can occur with a predetermined applied force or even cutting the mandrel in two. When the slip or slips are extended to the surrounding tubular for the anchoring function there is a reaction force from the surrounding tubular radially back through the slips. Depending on the slip system design the reaction force can go circumferentially into a slip ring, as in US 2004/0244966; into an adjacent slip circumferentially when slip segments make a continuous ring, as in U.S. Pat. No. 7,222,669; or into the mandrel through a cone that has a plurality of ramps as in US2012/0285684. Barrel slips are cylindrically shaped cohesive structures that can take radial reaction load and spread it circumferentially especially when used with multi-ramped drive cones. Barrel slips are shown in FIG. 4 of U.S. Pat. No. 6,481,497.
Other designs that use opposed single ramp cones that are brought together under opposed ends of slip segments have a unique way of directing the reaction force from the surrounding tubular when the slips are set radially into the actuation cones. What can happen is that the reaction force can be so great as to cause the mandrel beneath the cones to plastically deform if not collapse. This issue could be addressed with a thicker wall on the mandrel but then the price of that design choice is a much smaller passage through the mandrel for production. Another approach is to make the mandrel of rather high modulus materials but then in the event of a need to mill out the packer for any reason the milling becomes problematic or protracted. Similarly space constraints often limit the cone thickness that can be used between the mandrel and the slips and making a thicker cone will generally mean having to make other parts thinner to offset the cone dimension increase. Doing this creates pressure rating issues for the mandrel or else a smaller through bore needed to regain a desired pressure rating.
What is needed and provided by the present invention is a simple way to offset reaction force so as to minimize loading on the mandrel that can lead to undesirable deformation of the mandrel. In essence a sleeve is interference fit in the cone so that the fitment results in tensile hoop stress at the cone outer surface when running in. As the packer is set and the reaction force comes from the surrounding tubular through the slips and cones there is a tendency to place the outer cone surface in compression hoop stress. The initial hoop tension from the interference fitted sleeve offsets the compression hoop stress component resulting from the reaction force thereby minimizing the stress transmitted to the mandrel from the cone. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated FIGURE while recognizing that the full scope of the invention is to be determined from the appended claims.